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WinBioControlUnit function (winbio.h)

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Allows the caller to perform vendor-defined control operations on a biometric unit. Starting with Windows 10, build 1607, this function is available to use with a mobile image. This function is provided for access to extended vendor operations for which elevated privileges are not required. If access rights are required, call the WinBioControlUnitPrivileged function.

Syntax

HRESULT WinBioControlUnit(
  [in]            WINBIO_SESSION_HANDLE SessionHandle,
  [in]            WINBIO_UNIT_ID        UnitId,
  [in]            WINBIO_COMPONENT      Component,
  [in]            ULONG                 ControlCode,
                  PUCHAR                SendBuffer,
  [in]            SIZE_T                SendBufferSize,
                  PUCHAR                ReceiveBuffer,
  [in]            SIZE_T                ReceiveBufferSize,
                  SIZE_T                *ReceiveDataSize,
  [out, optional] ULONG                 *OperationStatus
);

Parameters

[in] SessionHandle

A WINBIO_SESSION_HANDLE value that identifies an open biometric session. Open a synchronous session handle by calling WinBioOpenSession. Open an asynchronous session handle by calling WinBioAsyncOpenSession.

[in] UnitId

A WINBIO_UNIT_ID value that identifies the biometric unit. This value must correspond to the unit ID used previously in the WinBioLockUnit function.

[in] Component

A WINBIO_COMPONENT value that specifies the component within the biometric unit that should perform the operation. This can be one of the following values.

Value Meaning
WINBIO_COMPONENT_SENSOR
 Send the command to the sensor adapter.
WINBIO_COMPONENT_ENGINE
 Send the command to the engine adapter.
WINBIO_COMPONENT_STORAGE
 Send the command to the storage adapter.

[in] ControlCode

A vendor-defined code recognized by the biometric unit specified by the UnitId parameter and the adapter specified by the Component parameter.

SendBuffer

Address of the buffer that contains the control information to be sent to the adapter specified by the Component parameter. The format and content of the buffer is vendor-defined.

[in] SendBufferSize

Size, in bytes, of the buffer specified by the SendBuffer parameter.

ReceiveBuffer

Address of the buffer that receives information sent by the adapter specified by the Component parameter. The format and content of the buffer is vendor-defined.

[in] ReceiveBufferSize

Size, in bytes, of the buffer specified by the ReceiveBuffer parameter.

ReceiveDataSize

Pointer to a SIZE_T value that contains the size, in bytes, of the data written to the buffer specified by the ReceiveBuffer parameter.

[out, optional] OperationStatus

Pointer to an integer that contains a vendor-defined status code that specifies the outcome of the control operation.

Return value

If the function succeeds, it returns S_OK. If the function fails, it returns an HRESULT value that indicates the error. Possible values include, but are not limited to, those in the following table. For a list of common error codes, see Common HRESULT Values.

Return code Description
E_HANDLE
 The session handle is not valid.
E_INVALIDARG
 The value specified in the ControlCode parameter is not recognized.
E_POINTER
 The SendBuffer, ReceiveBuffer, ReceiveDataSize, OperationStatus parameters cannot be NULL.
WINBIO_E_INVALID_CONTROL_CODE
 The value specified in the ControlCode parameter is not recognized.
WINBIO_E_LOCK_VIOLATION
 The biometric unit specified by the UnitId parameter must be locked before any control operations can be performed.

Remarks

You must call WinBioLockUnit before calling WinBioControlUnit. The WinBioLockUnit function creates a locked region in which vendor-defined operations can be securely performed.

Vendors who create plug-ins must decide which extended operations are privileged and which are available to all clients. To perform a privileged operation, the client application must call the WinBioControlUnitPrivileged function. The Windows Biometric Framework allows only clients that have the appropriate access rights to call WinBioControlUnitPrivileged.

To use WinBioControlUnit synchronously, call the function with a session handle created by calling WinBioOpenSession. The function blocks until the operation completes or an error is encountered.

To use WinBioControlUnit asynchronously, call the function with a session handle created by calling WinBioAsyncOpenSession. The framework allocates a WINBIO_ASYNC_RESULT structure and uses it to return information about operation success or failure. The WINBIO_ASYNC_RESULT structure is returned to the application callback or to the application message queue, depending on the value you set in the NotificationMethod parameter of the WinBioAsyncOpenSession function.

  • If you choose to receive completion notices by using a callback, you must implement a PWINBIO_ASYNC_COMPLETION_CALLBACK function and set the NotificationMethod parameter to WINBIO_ASYNC_NOTIFY_CALLBACK.
  • If you choose to receive completion notices by using the application message queue, you must set the NotificationMethod parameter to WINBIO_ASYNC_NOTIFY_MESSAGE. The framework returns a WINBIO_ASYNC_RESULT pointer to the LPARAM field of the window message.
To prevent memory leaks, you must call WinBioFree to release the WINBIO_ASYNC_RESULT structure after you have finished using it.

Requirements

Requirement Value
Minimum supported client Windows 7 [desktop apps only]
Minimum supported server Windows Server 2008 R2 [desktop apps only]
Target Platform Windows
Header winbio.h (include Winbio.h)
Library Winbio.lib
DLL Winbio.dll

See also

WinBioControlUnitPrivileged

WinBioLockUnit